A vegetable crop planting guide for new gardeners

On Oct. 5, I cut the garden’s last three summer squash. They came from a small bed of plants sown in early August, plants that produced double handfuls of yellow crooknecks in late September, enough for the family with extra to give away. A hard frost hit that early October night and by mid-morning the huge spiny leaves lay wilted on the ground, water-soaked and dark green like cooked spinach. Small yellow finger-length fruits leaked from ice-ruptured cells.

The same freeze took out most of our tomatoes, as well. Yes, I saw it coming and could probably have saved the plants with row covers, but I am not inclined toward such efforts. I prefer to garden with the seasons, letting the first hard frost bring an end to tender crops. Late summer plantings of tender vegetables are a gamble, but the odds on success seem to be increasing; some years you can get away with it. Maine’s climate is changing and the hallmark of that change is unpredictability.

Vegetable crops can be sorted into four hardiness groups: very tender, tender, half-hardy and hardy. In addition to summer squash and most tomato varieties, very tender vegetables, those likely to be killed by even a light frost, include cucumbers, melons, eggplants and peppers. Some may be severely damaged when night temperatures suddenly dip below 40 degrees but stay above freezing, a response called chilling injury.

Tender crops, including beans, corn, winter squash, and tomato varieties that originate from cooler climates, are not frost tolerant but can handle cool night temperatures. It may still make sense, however, to pull them up in late summer as their productivity wanes and replace them with fast-growing hardy crops such as broccoli or edible-pod peas.

Half-hardy vegetables, those that can take a light frost (but not a hard freeze) include beets, carrots, cauliflower, potato and lettuce. The crops that will withstand a hard frost, the truly hardy crops, include broccoli, cabbage, peas, onions, radishes, turnips and spinach. Together, these two groups are the mainstay of the spring and fall garden.

Begin the garden year by sowing peas as soon as the soil can be worked. The exact date will vary from year to year, depending on both temperature and the combination of snowmelt and spring rain. I like to wait until the weather settles somewhat and typically get my peas in the ground in the first week of May. Many of my gardening friends beat me by at least two weeks, but some years, when the spring turns wet and chilly in late April, the peas in those earliest sowings never germinate.

The rest of the hardy and half-hardy crops are planted as spring advances, some direct sown (see sidebar), others, such as broccoli and cabbage, transplanted in early May as seedlings that were started indoors in early April or purchased from local garden centers.

Tender and very tender crops should not be planted until soil temperatures are consistently above 60 degrees. I place a soil thermometer in one of the garden beds and hold off on planting these crops until the temperature registers 60 degrees for several consecutive days. This is the hardest waiting period, often extending well into June, but experience has proven that jumping the gun leads to poor or no germination for direct-sown crops and poor growth of transplants.

The cucurbits, including cucumbers, melons and squashes (both summer and winter) are typically planted as seedlings. I have been successful with direct sowing summer squash in early August for fall harvest, keeping the young plants under a row cover to protect them from slug damage. The row cover should be removed when the plants start flowering and by then the slugs will be thwarted by spines on the stems and leaf stalks.

Use the above information as a guide for your first year of vegetable gardening, but remember that these are guidelines and that no two gardens are alike. New lessons are learned every year as you fine tune your sense of place.